1. Field of the Invention
The invention relates to the need to accurately and easily position light sources in general and arc-lamps specifically.
2. Description of the Prior Art
For optimum performance, the relative positions of the lamp, its reflector, and the optical axis require a critical mutual alignment. An array of mechanical approaches have been employed to satisfy this task, but, they are cumbersome and interrelated resulting in an awkward trial-and-error procedure. This inconvenience is amplified because the relative short lifetime of some lamps requires a frequent replacement and, in the case of arc lamps, the short-term variation of arc position relative to its mounting sockets necessitates a continuing realignment.
It is an object of this invention to provide a lamp housing.
It is another object of this invention to provide a lamp housing that minimizes the alignment procedures associated with initial (and replacement) lamp installation.
It is a further object of this invention to achieve a critical portion of this alignment in an accurate manner either manually or automatically.
These goals are attained by mounting the movable light source on an assembly that can develop error signals that detect off axis conditions modifying the lamp reflector to generate a beam of light that develops the necessary position error signals to either manually or automatically position a movable lamp assembly to its proper location in this location in the vertical plane. The beam is formed by machining a small hole in the reflector on its optical axis. The small portion of light that passes through this aperture forms a tightly-defined beam that angularly moves proportionally to the angular movement of the lamp""s arc relative to the aperture. A sensing plate is located a short distance behind the reflector, The angular displacement of the light on this plate provides a visual indication of the direction and magnitude of any offset from the desired reference axis. For automatic correction of an offset condition, a photo sensor array in the sensing plate develops the necessary logic signals as inputs to a closed loop servo system. In the automatic mode, cam-driven servos can the movable lamp assembly to drive through a search envelope that results in the beam of light impinging on the photo detectors and, thereby, generating the error information to position the arc on the desired optical axis.
An advantage of the present invention is that the alignment of the arc lamp in the vertical plane is accomplished accurately and, if desired, automatically.
Another advantage of the present invention is that the servo drive mechanism has been designed to eliminate any possibility of encountering mechanical travel limits and inherent logic provides a search pattern to achieve on-axis lockup regardless of initial lamp positions.
These and other objects and advantages of this invention will be evidenced after reading the detailed description of the preferred embodiments as applied to a microscope""s arc-lamp housing. Details are illustrated in the following drawings.